CONSOLIDATED INVESTMENT PRODUCTS - Fair Value Hierarchy Levels of Investments Held and Notes Issued by Consolidated Investment Products (Details) - USD ($) $ in Millions | Sep. 30, 2023 | Dec. 31, 2022 |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Total assets at fair value | $ 8,612.9 | $ 8,531.4 |
Consolidated | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Real estate investments | 479.4 | 552 |
Total assets at fair value | 8,612.9 | 8,531.4 |
Consolidated | Quoted Prices in Active Markets for Identical Assets (Level 1) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Real estate investments | 0 | 0 |
Total assets at fair value | 125.6 | 177.5 |
Consolidated | Significant Other Observable Inputs (Level 2) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Real estate investments | 0 | 0 |
Total assets at fair value | 6,956.2 | 6,979.7 |
Consolidated | Significant Unobservable Inputs (Level 3) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Real estate investments | 0 | 0 |
Total assets at fair value | 650.5 | 368.6 |
Consolidated | Investments Measured at NAV as a practical expedient | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Real estate investments | 479.4 | 552 |
Total assets at fair value | 880.6 | 1,005.6 |
Consolidated | Bank loans | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 6,679.2 | 6,315.1 |
Consolidated | Bank loans | Quoted Prices in Active Markets for Identical Assets (Level 1) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 0 | 0 |
Consolidated | Bank loans | Significant Other Observable Inputs (Level 2) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 6,127.7 | 6,069.8 |
Consolidated | Bank loans | Significant Unobservable Inputs (Level 3) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 551.5 | 245.3 |
Consolidated | Bank loans | Investments Measured at NAV as a practical expedient | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 0 | 0 |
Consolidated | Bonds | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 683.2 | 697.5 |
Consolidated | Bonds | Quoted Prices in Active Markets for Identical Assets (Level 1) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 10.7 | 8.8 |
Consolidated | Bonds | Significant Other Observable Inputs (Level 2) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 672.5 | 688.2 |
Consolidated | Bonds | Significant Unobservable Inputs (Level 3) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 0 | 0.5 |
Consolidated | Bonds | Investments Measured at NAV as a practical expedient | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 0 | 0 |
Consolidated | Equity securities, Equity and fixed income mutual funds | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 203.9 | 274.9 |
Equity and fixed income mutual funds, and investments in other private equity funds | 166 | 230.7 |
Consolidated | Equity securities, Equity and fixed income mutual funds | Quoted Prices in Active Markets for Identical Assets (Level 1) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 87.5 | 129.9 |
Equity and fixed income mutual funds, and investments in other private equity funds | 27.4 | 38.8 |
Consolidated | Equity securities, Equity and fixed income mutual funds | Significant Other Observable Inputs (Level 2) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 17.4 | 29.8 |
Equity and fixed income mutual funds, and investments in other private equity funds | 138.6 | 191.9 |
Consolidated | Equity securities, Equity and fixed income mutual funds | Significant Unobservable Inputs (Level 3) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 99 | 115.2 |
Equity and fixed income mutual funds, and investments in other private equity funds | 0 | 0 |
Consolidated | Equity securities, Equity and fixed income mutual funds | Investments Measured at NAV as a practical expedient | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Bank loan, bonds and equity securities | 0 | 0 |
Equity and fixed income mutual funds, and investments in other private equity funds | 0 | 0 |
Consolidated | Investments in other private equity funds | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Equity and fixed income mutual funds, and investments in other private equity funds | 401.2 | 461.2 |
Consolidated | Investments in other private equity funds | Quoted Prices in Active Markets for Identical Assets (Level 1) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Equity and fixed income mutual funds, and investments in other private equity funds | 0 | 0 |
Consolidated | Investments in other private equity funds | Significant Other Observable Inputs (Level 2) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Equity and fixed income mutual funds, and investments in other private equity funds | 0 | 0 |
Consolidated | Investments in other private equity funds | Significant Unobservable Inputs (Level 3) | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Equity and fixed income mutual funds, and investments in other private equity funds | 0 | 7.6 |
Consolidated | Investments in other private equity funds | Investments Measured at NAV as a practical expedient | | |
Segment Reporting, Other Significant Reconciling Items [Line Items] | | |
Equity and fixed income mutual funds, and investments in other private equity funds | $ 401.2 | $ 453.6 |